Pressure switch having pressure hose connection through case and diaphragm

ABSTRACT

A pressure switch, for controlling the water level in a washing machine, is formed by a casing closed at one end by a flexible diaphragm fitted to a rim of the casing, a dished rigid cover fitted over the diaphragm to define a pressure chamber and an electric switch disposed within the casing for operation by movement of the diaphragm in response to pressure changes in the chamber. The pressure inlet to the chamber is formed by a pipe connection integral with the casing and having an outlet communicating with the chamber via a passage which passes through the rim of the casing, through a portion of the diaphragm sealed between the rim of the casing and the cover and through a channel formed on the inside of the cover.

United States Patent 1 1 Pijpers [4 Oct. 1, 1974 54] PRESSURE swrrcrrHAWNG rRrssrJRE 3,617,665 11/1971 Berson 200/83 R HUSE CONNECTIONTHROUGH CASE AND Primary Examiner-Robert K. Schaefer MAPHRAGMI A E G IdP T l ssistam xaminerera o in [75] Inventor ggmg i ii Velp Attorney,Agent, or FirmMichael, Best & Friedrich [73] Assignee: @ontrols Company0t America, 57 ABSTRACT Schlller Park A pressure switch, for controllingthe water level in a [22] Filed: Sept. 26, 1973 washing machine, isformed by a casing closed at one end by a'flexible diaphragm fitted to arim of the cas- [21] Appl' 400808 ing, a dished rigid cover fitted overthe diaphragm to define a pressure chamber and an electric switch dis-[30] Foreign Application Priority Data posed within the casing foroperation by movement of Sept. 27, 1972 Great Britain 44562/72 thediaphragm in response to P Changes in the chamber. 1521 Us. cu 200/83 sThe pressure inlet to the Chamber is formed y a 511 in. C1. H01h 35/341P connection integral with the, casing and having an 53 Field M Search200 B, 3 R, 83 WM, outlet communicating with the chamber via a passage200/83 N, 83 S, 83 V which passes through the rim of the casing, througha portion of the diaphragm sealed between the rim of 5 References (Ii/edthe casing and the cover and through a channel UNITED STATES PATENTSfonned on the inside of the cover.

3,566,060 2/1971 Phillips 200/83 R 1 Claim, 4 Drawing Figures W he 77 10PAIENIEDHBT 11914 W w a 3.839.609

E IENI uum 1mm sum ear 2 This invention relates to pressure switches, inparticular those for use in washing machines to control the level ofwater in the machine.

Such pressure switches conventionally comprise a cylindrical casing ofplastics or metal which is closed at one end and contains one or moreelectric switches, a flexible diaphragm mounted on a rim at the oppositeend of the casing and closing this end, and a dished cover which fits onto the rim of the casing and holds the periphery of the diaphragm inposition, the cover being spaced from the diaphragm to form therebetweena pressure chamber which communicates with a pipe connection, mounted onthe pressure switch casing, the pipe connection being coupled to an airtrap in the washing machine via a flexible coupling pipe. The diaphragmis movable in dependence upon the pressure in the pressure chamber andhas a mechanical connection to the switch or each switch to operate theswitch in dependence upon the position of the diaphragm.

It is known to provide a cover made of plastics material in which thepipe connection is moulded integrally and to clamp the cover to thecasing by means of a metal clamping ring. The use of a pipe connectionintegral with a plastics cover however increases the depth of the coverand hence the overall depth of the pressure switch, which is undesirablesince such switches have to be accommodated in a washing machine in avery re stricted space. It is convenient for the cover to be made ofmetal so that it can be formed integrally with a clamping ring, the edgeof the ring being bent under the rim of the casing to seal the cover,the diaphragm and the casing to each other. However the attachment of apipe coupling to such a cover involves soldering and plating andconsequently is expensive.

According to the present invention, there is provided a pressure switchcomprising a casing having an opening at one end surrounded by a rim ofthe casing, a flexible diaphragm covering said opening, one or moreelectric switches in the casing operable by movement of the diaphragm,and a cover fltted'to the rim of the casing and forming a pressurechamber with said diaphragm, a pipe connection rigid with the casing andhaving an outlet passage opening beneath the cover, and a communicatingpassage formed in the cover from said outlet passage to the pressurechamber.

The present invention also provides a pressure switch comprising acylindrical casing open at one end and having a pipe connection integralwith a cylindrical wall of the casing and extending therefrom, the pipeconnection having a lateral outlet disposed adjacent said open end ofthe casing, a flexible diaphragm fitted to a rim of the casing at saidopen end, one or more electrical switches mechanically connected to thediaphragm for operation thereby, a substantially rigid dished coverlocated over the diaphragm and sealed to said rim to form a pressurechamber between the cover and the diaphragm and a passage extendingbetween the chamber and the pipe connection via a part of the diaphragmwhich is sealed to the rim of the casing.

One embodiment of the invention is illustrated, by way of example, inthe accompanying drawing in which:

FIG. 1 is a section through a pressure switch according to theinvention;

FIGS. 2 and 3 respectively are a plan and a perspective section of partof the switch of FIG. 1; and

FIG. 4 is a partial section on the line lV-IV of FIG.

As shown in the drawing, the pressure switch comprises a cylindricalplastics casing 10 closed at its lower end, the cylindrical wall of thecasing having an integral radially extending pipe connection 11, and thepipe connection having a lateral outlet 12 formed in the thickened rim13 of the casing which surrounds its open upper end.

A diaphragm 14 of rubber or other flexible material has a peripheralbeading 15 which fits into a seating 16 extending around the rim of thecasing. At the position at which the lateral outlet passes through therim, the peripheral beading divides and rejoins to form an eyelet 17registering with the outlet 12 and providing an opening through thebeading.

At the centre of the diaphragm is a metal plate 18 which is connectedthrough a post 20 to the switch or each switch of the pressure switchassembly.

A sheet'metal dished cover 21 has a peripheral flange 22 which, when thecover is in position, is folded over the rim of the casing so as topress the beading of the diaphragm between the cover and the casing rim.However, at the position at which the pipe connection joins the casing,the flange of the cover has a generally flattened area which extendsinto the dished portion of the cover and overlies the eyelet. This areais traversed by a semi-cylindrical groove formed on the underside of thecover which provides a communicating passage 23 extending in oppositedirections from the space within the eyelet 17 of the beading, acrossthe eyelet, and opens at its opposite end portions into the dishedportion of the cover. In order to imgrove sealing between the flange ofthe cover and the eading, the flange of the cover is impressed on itsouter surface to produce ridges 25 on the inner surface extending along,and in contact with, the beadin Thus, in operation, fluid pressure istransmitted through the outlet 12 of the pipe connection, through theeyelet 17 of the diaphragm beading, and in opposite directions throughthe two end portions of the communicating passage 23 into the pressurechamber 24 formed between the cover 21 and the diaphragm 14.

I claim:

1. A pressure switch comprising,

a casing having a cylindrical wall having a rim defining an open end ofthe casing,

a hose connection integral with the casing and leading to a conduitformed in the casing,

a boss projecting from said rim,

said conduit leading through said boss,

a flexible diaphragm covering said open end and having a peripheral beadseated on said rim with an eyelet formed in the bead to fit around saidboss whereby the conduit projects through the boss centrally of saideyelet,

a switch mounted in the casing and operatively connected to thediaphram,

a cover fitting over the diaphragm and forming a pressure chamber incooperation with the diaphragm,

said cover having a flange overlying said bead and fonned to secure thecover to the casing, said flange having a channel formed thereincommunicating with the space between said conduit and the cover at oneend and communicating with said pressure chamber at the other end of thechannel.

1. A pressure switch comprising, a casing having a cylindrical wallhaving a rim defining an open end of the casing, a hose connectionintegral with the casing and leading to a conduit formed in the casing,a boss projecting from said rim, said conduit leading through said boss,a flexible diaphragm covering said open end and having a peripheral beadseated on said rim with an eyelet formed in the bead to fit around saidboss whereby the conduit projects through the boss centrally of saideyelet, a switch mounted in the casing and operatively connected to thediaphram, a cover fitting over the diaphragm and forming a pressurechamber in cooperation with the diaphragm, said cover having a flangeoverlying said bead and formed to secure the cover to the casing, saidflange having a channel formed therein communicating with the spacebetween said conduit and the cover at one end and communicating withsaid pressure chamber at the other end of the channel.